The present invention relates to a texturing apparatus for applying a texturing to a magnetic recording medium (magnetic recording disc) and a magnetic recording medium applied with the texturing, and more specifically, it relates to a texturing apparatus utilizing a laser beam and to a magnetic recording medium formed by using a substrate obtained by the texturing apparatus.
In a magnetic recording disc (hard disk) device for conducting reading/writing operation with a magnetic head rising from a disc, for stably maintaining a minute gap between the head and the disc, a so-called contact start and stop (CSS) system is used in which the magnetic head stops stationary in contact with the surface of the magnetic recording disc during stopping (not reading/writing state), while the magnetic head takes off and flys over the surface of the magnetic recording disc.
In the CSS system, the texturing is usually applied for forming fine traces to a CSS zone to reduce the contacting area between the head and the disc for preventing sticking abrasion or damage of the head.
For the texturing, a mechanical polishing of using a polishing tape coated with grinding particles dispersed in a binder or using a slurry containing polishing grains dispersed therein has been used generally.
However, as the magnetic recording disc device has been miniaturized in recent years, a motor used for the device also tends to be miniaturized in the size and the torque of the motor during driving is lowered as well. Therefore, no sufficient reduction of the contacting area can be obtained by the existent texturing method, so that attraction force of the head to the disc surface during stopping becomes greater than the torque of the motor to bring about a problem of sticking that hinders startings.
In addition, for improving a recording density, a flying height of the head has tended to be lowered, and accompanying therewith, the fabrication with lower and more uniform height has been demanded for texturing applied to the CSS zone.
However, in the existent texturing by mechanical polishing, it becomes difficult to control the uniformity and the fabrication height and can not cope with the recent demand. In view of the above, the texturing utilizing a Q switch YAG laser beam of narrow pulse width and high power is proposed as an alternative method in U.S. Pat. No. 5,062,021. The method disclosed in the said U.S. Pat. No. 5, 062, 021 comprises forming crater-like unevenness projections composed of a hole formed by melting and a circular rim formed therearound by being raised with the surface tension and solidified.
The texturing using the laser beam allows more easy control for the absolute height and the uniformity as compared with the existent mechanical polishing and it is considered to be a promising fabrication method in the future. However, no actual fabrication device has been considered in view of industrial production in the said U.S. Pat. No. 5,062,021.
As a result of the present inventors' earnest studies, it has been found that a magnetic recording medium obtained by using a texturing apparatus comprising: a substrate rotating means which is rotatable while holding a substrate; a laser beam source capable of continuously outputting a laser beam; a modulation means for ON/OFF control of a laser beam from the laser beam source by a pulse frequency from 0.1 to 10 MHz; a focusing means for irradiating a modified laser beam outputted from the modulation means at a spot diameter of 0.2 to 4 .mu.m to the surface of the substrate held by a substrate rotating means; and a moving means for relatively moving the laser beam outputted from the focusing means to the substrate rotating means, has a satisfactory CSS (contact start and stop) characteristic, an excellent sticking property of the magnetic head to the surface of the magnetic recording medium, and is capable of lowering a flying height of the magnetic head. On the basis of the finding, the present invention has been attained.